Samsung is now showcasing the many Galaxy S4 accessories on its new GS4 microsite. The Game Pad is listed as supporting devices up to 6.3-inches . As Engadget pointed out, that's "bigger than the 5.5-inch Galaxy Note II and smaller than the 7-inch Galaxy Tab line". It has been rumored that Samsung plans to launch a 6.3-inch Galaxy Note III, so that could be the reason for the oddly specific dimensions.
Samsung unveiled the Game Pad along with the S Band, S View Cover, Wireless Charging Pad / Cover, and Body Scale at its Unpacked event in New York on Thursday. It's unknown how much the gaming controller will cost, and when it will be available. The microsite also lists Flip Covers in a variety of colors, an extra battery pouch, a GS4 headset, and an HRM running band as some of the other GS4 accessories that will be available in the future.